JP6446039B2 - Magnetic levitation device and control method thereof - Google Patents

Description

  The present invention relates to a magnetic levitation apparatus that uses a magnetic force to support a floating object in a non-contact manner and a control method thereof, and realizes stable non-contact support of the floating object at a low cost.

The magnetic levitation system can support an object without contact, has little vibration and noise because there is no mechanical friction, and does not require lubrication. Can be used in special environments.
Magnetic levitation methods include a repulsive type that uses the repulsive force between magnets, and an attractive type that uses the attractive force of a magnet and a ferromagnetic material.
FIG. 17A shows a state in which the ferromagnetic body 11 existing between the pair of electromagnets 10 is attracted by the magnetic force of the upper and lower electromagnets 10 and is supported in a non-contact manner between the electromagnets. The vertical position of the ferromagnetic material 11 can be stably maintained by controlling the current applied to the upper and lower electromagnets 10 and adjusting the magnetic force generated from the electromagnets 10.

When an external force in a direction orthogonal to the arrangement direction of the pair of electromagnets 10 is applied to the ferromagnetic body 11 as shown in FIG. 17B, the non-contact supported ferromagnetic body 11 is pushed. Move in the direction (lateral shift). At this time, as shown in FIG. 18, a force including a component of the restoring force A that attempts to restore the lateral displacement is applied to the end of the ferromagnetic material 11 that is separated from the electromagnet 10 together with the component of the attractive force B. . This is known as the “end effect”.
The ferromagnetic material 11 that has received the restoring force A is laterally shifted to the opposite side of the lateral displacement direction and receives the restoring force due to the end effect again. As a result, the ferromagnetic material 11 repeats vibration in the lateral displacement direction.
As described in Patent Document 1 below, the vibration in the lateral slip direction is difficult to converge because the damping action does not act on the non-contact-supported ferromagnetic material 11.

JP 2001-268881 A

As shown in FIG. 19, the vibration in the lateral displacement direction is not limited to the vertical direction of the ferromagnetic body 11, but a pair of electromagnets 12 is arranged not only in the front-rear and left-right directions, but in the same manner as the upper and lower electromagnets 10. This can be suppressed by controlling the current applied to the electromagnet 12 and adjusting the magnetic force generated from the electromagnet 12.
However, in the case of such a configuration, the number of electromagnets and amplifiers for supplying current to the electromagnets increases, and the size and cost of the apparatus cannot be avoided.

  The present invention was devised in view of such circumstances, and provides a magnetic levitation device that has a vibration damping function in the direction of lateral displacement, can be configured at a low cost, and a control method therefor. It is aimed.

The present invention relates to a magnetic levitation device that supports a floating object in a non-contact manner using magnetic force, a pair of magnets that generate a magnetic force for non-contact support of the floating object, and an arrangement direction of the pair of magnets Displacement detecting means for detecting the displacement of the levitated object in the lateral displacement direction orthogonal to the horizontal axis, and control means for suppressing vibration in the lateral displacement direction of the levitated object, and the control means is displaced in a direction away from the center of vibration. The pair of magnets is controlled so that a stronger magnetic force acts on the floating object to be moved than when moving in a direction returning to the center of vibration.
In this way, by increasing the rigidity of the magnetic force when the levitating object moves away from the center of vibration, and by reducing the rigidity of the magnetic force when the levitating object returns to the center of vibration, the vibration of the levitating object rapidly Attenuates.

In the magnetic levitation apparatus of the present invention, the pair of magnets is composed of electromagnets arranged in the vertical direction, and the levitation object is attracted to each of the electromagnets and is supported in a non-contact manner between the pair of electromagnets. Contains the body. The control means increases the current applied to the pair of electromagnets when the levitating object is displaced in a direction away from the center of vibration, and applies to the pair of electromagnets when the levitating object is displaced in a direction returning to the center of vibration. Decrease the current.
With such a configuration, it is possible to effectively attenuate the vibration in the lateral displacement direction of the attraction type magnetic levitation device.

Further, in the magnetic levitation apparatus of the present invention, when the displacement of the levitating object that vibrates in the lateral displacement direction is x and the moving speed of the levitating object is x ′, the control means applies the bias current applied to the pair of electromagnets, x × x ′ (hereinafter referred to as x · x ′) ≧ 0 and x · x ′ <0, and the bias current when x · x ′ ≧ 0 is x · x 'Set to be larger than the bias current when <0.
In the x-coordinate with the origin of the vibration in the lateral displacement direction, x · x ′ ≧ 0 is when x and x ′ are both positive or negative, and the levitated object moves away from the vibration center. It is in a state displaced in the direction. X · x ′ <0 is when x is positive and x ′ is negative, or when x is negative and x ′ is positive, and the floating object is displaced in the direction of returning to the center of vibration. It is in a state. Therefore, increase the bias current applied to the pair of electromagnets when x · x ′ ≧ 0 to increase the rigidity of the magnetic force, and decrease the bias current when x · x ′ <0 to decrease the rigidity of the magnetic force. Thus, it is possible to effectively attenuate the vibration in the lateral displacement direction of the floating object.

In the magnetic levitation apparatus of the present invention, when the value of x · x ′ is smaller than the predetermined value, the control means decreases the bias current applied to the pair of electromagnets according to the value of x · x ′. Also good.
If the bias current value when the value of x · x ′ is small is large, the overshoot amount of the levitated object becomes large, and there is a possibility that the time until the convergence of the vibration becomes long. Such a fear can be eliminated by reducing the bias current according to the value of x · x ′.

Further, in the magnetic levitation apparatus of the present invention, the displacement detection means can be constituted by a measurement means that measures the distance to the levitation object and is arranged in the lateral displacement direction of the levitation object.
From the change in the distance to the floating object detected by the measuring means, the value of x · x ′ and the value of x · x ′ can be obtained.

Further, in the magnetic levitation apparatus of the present invention, the displacement detection means can also be configured by a sensing coil that is disposed on the side of the electromagnet facing the levitating object and detects a change in passing magnetic flux.
When the magnetic flux passing through the sensing coil tends to decrease, the levitated object is displaced away from the center of vibration, and when the magnetic flux passing through the sensing coil tends to increase, the levitating object vibrates. It is when it is displaced in the direction to return to the center of. The state of the displacement can be detected from changes in the induced electromotive force and induced current of the sensing coil.

In the magnetic levitation apparatus of the present invention, the displacement detection means may be configured by a force sensor that supports the electromagnet and detects the force acting on the electromagnet.
When the detected value of the force sensor tends to decrease, the levitated object is displaced in a direction away from the center of vibration, and when the detected value of the force sensor tends to increase, the levitated object vibrates. It is when it is displaced in the direction to return to the center of.

In the magnetic levitation apparatus of the present invention, the levitating object includes a magnet that repels in a direction opposite to the pair of magnets, and the levitating object is non-induced by the repulsive force between the pair of magnets and the magnet of the levitating object. Touch supported. The control means moves the pair of magnets to a position where the repulsive force is strengthened when the levitating object is displaced in a direction away from the center of vibration, and the repulsive force is displaced when the levitated object is displaced in a direction returning to the center of vibration. Move the pair of magnets to a weakened position.
With such a configuration, it is possible to effectively attenuate the vibration in the lateral displacement direction of the repulsive magnetic levitation device.

The present invention relates to a method for controlling a magnetic levitation apparatus that supports a levitating object in a non-contact manner using magnetic force, and the levitating object including a ferromagnetic material is not interposed between a pair of electromagnets arranged vertically. A current i for supporting and supporting a pair of electromagnets to suppress displacement of the levitating object in the arrangement direction of the electromagnets and a bias current Δi for suppressing vibration of the levitating object in the lateral displacement direction orthogonal to the arrangement direction. Apply by overlapping. When the displacement of the flying object vibrating in the lateral displacement direction is x and the moving speed of the flying object is x ′, the bias current Δi applied to the pair of electromagnets is expressed as x · x ′ ≧ 0 and x Switching between x ′ <0 and the bias current when x · x ′ ≧ 0 is larger than the bias current when x · x ′ <0.
By such a control method, a levitated object can be stably supported in a non-contact manner using a pair of electromagnets.

In the method of controlling a magnetic levitation apparatus according to the present invention, when the value of x · x ′ is smaller than a predetermined value, the bias current Δi to be applied may be decreased according to the value of x · x ′.
By doing so, it is possible to prevent an excessive amount of the levitated object from increasing, and it is possible to shorten the time until the vibration converges.

In the method of controlling a magnetic levitation apparatus according to the present invention, the bias current Δi may be changed according to a function f (x · x ′) that satisfies the following conditions 1 to 5.
A parameter for adjusting the range in which the bias current Δi continuously changes is X ₀ ,
Condition 1: When x · x ′ <− X ₀ f (x · x ′) = − ΔI
Condition 2: When −X ₀ <x · x ′ <0, monotonically increases from −ΔI to 0 Condition 3: f (0) = 0,
Condition 4: When 0 <x · x ′ <X ₀ , monotonically increases from 0 to ΔI Condition 5: When X ₀ <x · x ′ f (x · x ′) = + ΔI
If the bias current Δi is changed according to the function f satisfying these conditions 1 to 5, when the value of x · x ′ is small, the bias current Δi is also small, so that it is possible to prevent the overshoot amount of the flying object from increasing. .

  According to the present invention, a magnetic levitation device that can stably support a non-contact floating object can be configured in a small size and at a low cost.

The figure which shows the attraction | suction type magnetic levitation apparatus which concerns on the 1st Embodiment of this invention The figure which shows the state from which x * x 'of the floating object of FIG. 1 becomes positive or negative The figure which shows the locus | trajectory of x and x 'when the floating target object of FIG. Diagram showing experimental equipment Diagram showing disturbance waveform The figure which shows the transverse slip vibration waveform at the time of bias current 0 (a) and 1 A (b) The figure which shows the transverse slip vibration waveform when switching control of the bias current The figure which shows the change (a) of x * x ', and the bias current (b) by which switching control was carried out The figure which shows the locus | trajectory of x and x 'of the lateral slip vibration to converge The figure which shows the transverse slip vibration waveform when changing the bias current value and switching control The figure which shows the function which reduces a bias current in the small range of x * x ' FIG. 12 is a diagram showing a lateral vibration waveform when the bias current is controlled by the function of FIG. The figure which shows the composition when detecting the displacement of the floating object with the sensing coil The figure which shows a structure when detecting the displacement of a floating object with a force sensor The figure which shows the repulsion-type magnetic levitation apparatus based on the 2nd Embodiment of this invention The figure which shows the form when switching the rigidity of lateral slip vibration in the apparatus of FIG. The figure explaining the displacement of the levitating object in the attraction type magnetic levitation device The figure explaining the end effect of a magnetic levitation device A diagram showing a conventional lateral vibration suppression structure

(First embodiment)
FIG. 1 shows an attraction type magnetic levitation apparatus according to a first embodiment of the present invention.
This apparatus includes a pair of electromagnets 10 arranged in the vertical direction (z direction), a ferromagnetic body 11 that is a non-contact supported object between the pair of electromagnets 10, and a lateral displacement direction of the ferromagnetic body 11. A displacement sensor 20 that detects the amount of displacement in the (x direction) and a control mechanism 40 that controls the current applied to the electromagnet 10 are provided.

When a displacement signal (z) is input from a displacement sensor (not shown) that detects the displacement of the ferromagnetic material 11 in the z direction, the control mechanism 40 generates a z-direction bias current for eliminating the displacement in the z-direction by PID control. When the displacement signal (x) is input from the PID control unit 41 to be generated and the displacement sensor 20 that detects the displacement of the ferromagnetic material 11 in the x direction, the x direction bias current depends on the product of x and (dx / dt). From the bias current switching unit 47 for switching between, the inversion unit 42 for inverting the sign of the z-direction bias current output from the PID control unit 41, and the z-direction bias current and the bias current switching unit 47 output from the PID control unit 41 an adder 43 for adding the x-direction bias current output to the reference current I _0, or z-direction bias current and a bias current switching unit 47 which has been inverted is outputted from the inverter 42 An adder 44 for adding the x-direction bias current output to the reference current I _0, an amplifier 45 is applied to the upper electromagnet 10 by amplifying the current output from the adder 43 is output from the adder 44 And an amplifier 46 for amplifying the applied current and applying it to the lower electromagnet 10.

  Control for eliminating the displacement in the z direction has been well known. The control mechanism 40 is characterized in that an x-direction bias current is further superimposed on the current I applied to the electromagnet 10 in order to stably hold the floating object in the z direction. The same amount of x-direction bias current is added to the upper and lower electromagnets 10. Therefore, even if an x-direction bias current is applied, the z-direction balance of the ferromagnetic material 11 is not disturbed.

In this specification, (dx / dt) is expressed as x ′.
The sign function sgn (n) of the bias current switching unit 47 outputs 1 when n> 0, 0 when n = 0, and −1 when n <0. Therefore, the bias current switching unit 47 outputs ΔI as the x-direction bias current when x · x ′> 0, and outputs −ΔI as the x-direction bias current when x · x ′ <0. When x · x ′ = 0, 0 is output.
FIG. 2 shows a range where x · x ′> 0 and a range where x · x ′ <0 in an orthogonal coordinate system having x and x ′ as axes. x · x ′> 0 is the first quadrant and the third quadrant of the coordinate system. As shown in FIGS. 2A and 2C, the levitated object is the center position of the electromagnet 10 (center of vibration). It is a state when it leaves | separates from a horizontal shift direction. Further, x · x ′ <0 is in the second quadrant and the fourth quadrant, and as shown in FIGS. 2B and 2D, the laterally levitated object is positioned at the center position of the electromagnet 10 (center of vibration). This is the state when returning to).

Assuming that the current supplied to the electromagnet 10 in order to maintain the balance of the ferromagnetic material 11 in the z direction is I ₀ , when x · x ′> 0, a current (I ₀ + ΔI) is applied to the electromagnet 10, and x · When x ′ <0, a current (I ₀ −ΔI) is applied to the electromagnet 10.
If the current applied to the electromagnet 10 is increased, the magnetic force generated from the electromagnet 10 is enhanced, the restoring force in the lateral displacement direction with respect to the ferromagnetic body 11 is increased, and the rigidity against the lateral displacement of the floating object is increased.
Assuming that k + Δk is the rigidity against the lateral displacement when the current (I ₀ + ΔI) is applied to the electromagnet 10, the rigidity when the current (I ₀ −ΔI) is applied to the electromagnet 10 is reduced to k−Δk.

FIG. 3 shows the displacement and velocity trajectories on the xx ′ orthogonal coordinate system when vibrating in the lateral displacement direction. This trajectory changes when the rigidity against the lateral displacement is different. FIG. 3A shows a trajectory when the rigidity against the lateral displacement is high, and a long trajectory is drawn in the speed (x ′) direction. FIG. 3B shows a locus when the rigidity is low, and a long locus is drawn in the displacement (x) direction.
FIG. 3C shows a locus when the control mechanism of FIG. 1 switches the rigidity against the lateral displacement according to the sign of x · x ′. In this case, in the second and fourth quadrants, the trajectory when the rigidity is low is traced, and in the first and third quadrants, the trajectory when the rigidity is high is traced and the vibration is attenuated.
Thus, when the rigidity against lateral deviation is increased when x · x ′> 0 and the rigidity is lowered when x · x ′ <0, the vibration in the lateral deviation direction of the floating object rapidly converges. To do.

The characteristics of the magnetic levitation device were confirmed by experiments.
FIG. 4 shows a plan view of the experimental apparatus. This device includes electromagnets 51 and 52 arranged above and below the floating object 50, a laser displacement meter 54 that detects displacement in the lateral displacement direction of the floating object 50, and the displacement direction of the floating object 50 is limited to the lateral displacement direction. A leaf spring 55 to be restrained and a voice coil motor 53 that applies a disturbance in the lateral displacement direction to the flying object 50 are provided.
In this device, since the movement of the floating object 50 is restricted to one degree of translation in the lateral displacement direction using the leaf spring 55, only the bias current that suppresses the vibration in the lateral displacement direction is supplied to the electromagnets 51 and 52. Applied.

FIG. 5 shows the disturbance generated by the voice coil motor 53.
For comparison, FIG. 6A shows vibration in the lateral displacement direction of the flying object 50 when the bias current I to the electromagnets 51 and 52 is set to I = 0 and a disturbance is given to the flying object 50. ing. The frequency of this vibration was 3.5 Hz, and the settling time until the amplitude reached 5% of the initial value was measured and found to be 64.0 seconds.
For comparison, FIG. 6B shows vibration in the lateral displacement direction of the flying object 50 when the bias current I is set to I = 1A and a disturbance is given to the flying object 50. The frequency of this vibration was 4.3 Hz, and the settling time until the amplitude reached 5% of the initial value was 59.5 seconds.
From the comparison of the vibration frequencies shown in FIGS. 6A and 6B, it can be seen that the rigidity against the lateral displacement is increased by 44% by applying a bias current to the electromagnets 51 and 52. However, the vibration in the lateral displacement direction cannot be converged in a short time only by increasing the rigidity.

FIG. 7 shows that the bias current I applied to the electromagnets 51 and 52 is 1 A when the value of x · x ′ is positive, and 0 A when the value of x · x ′ is negative. The vibration in the lateral displacement direction is shown. FIG. 8 shows the bias current (x) to the electromagnets 51 and 52 switched according to the change (a) of x · x ′ obtained from the measured value of the laser displacement meter 54 and the sign of x · x ′. b).
The settling time until the vibration amplitude reached the initial 5% was 2.5 seconds. This is 1/25 of the vibration settling time shown in FIG.
FIG. 9 shows the trajectories of x and x ′, which are the basis of the calculation of xx ′ of FIG. 8, on the xx ′ orthogonal coordinates. From FIG. 9, it can be seen that the displacement and velocity converge to 0 so as to draw a spiral on the coordinates by switching the bias current to the electromagnets 51 and 52 and controlling the rigidity against the lateral displacement.

FIG. 10 shows the vibration in the lateral displacement direction when the stiffness control is performed by changing the magnitude of the bias current I applied to the electromagnets 51 and 52 when the value of x · x ′ is positive.
FIG. 10A shows the case where I ₀ = ΔI = 0.25 A, and the settling time was 4.9 seconds.
FIG. 10B shows the case where I ₀ = ΔI = 0.5 A, and the settling time was 2.4 seconds.
FIG. 10C shows the case where I ₀ = ΔI = 0.75 A, and the settling time was 0.9 seconds.
FIG. 10D shows the case where I ₀ = ΔI = 1.0 A, and the settling time was 1.0 second.
Thus, the settling time can be shortened to some extent by increasing the bias current. However, it should be noted that when I ₀ = ΔI = 1.0 A, the settling time is longer than when I ₀ = ΔI = 0.75 A.
This is considered that when I ₀ = ΔI = 1.0 A, the change in rigidity is large, so that the amount of overshooting is large when the displacement is small, which delays the convergence of vibration.
This point can be avoided by reducing the bias current applied in the state of x · x ′> 0 in accordance with the value of x · x ′ when the value of x · x ′ is smaller than the predetermined value.

FIG. 11 shows a bias current (a) generated by the bias current switching unit 47 (FIG. 1) using the sign function sgn, and arctangent (2 / π) tan ⁻¹ (αx · x ′) shows the bias current (b) generated using the function. When the arc tangent function is used, the bias current decreases in accordance with the value of x · x ′ in a small range of x · x ′. Thus, chattering is prevented from occurring in a small range of x · x ′. The range in which the bias current continuously changes can be adjusted by the parameter α. When α is small, the range in which the bias current continuously changes is wide, and when α is large, the range in which the bias current continuously changes can be narrowed. In particular, in the limit where α is infinite, it coincides with the sign function sgn.
FIG. 12 shows that the bias current I applied to the electromagnets 51 and 52 is α = 80 and I ₀ = ΔI = 1.0 A, and the arc tangent (2 / π) tan ⁻¹ (αx · x ′) function is used. The vibration in the lateral shift direction when generated is shown.
The vibration settling time is 0.95 seconds, which is shorter than the vibration settling time shown in FIG.

The function replaced with the sign function sgn is not limited to arctangent, and any function f that satisfies the following conditions can be used.
(1) When x · x ′ <− X ₀ f (x · x ′) = − ΔI
(2) When −X ₀ <x · x ′ <0, monotonically increases from −ΔI to 0 (3) f (0) = 0
(4) When 0 <x · x ′ <X ₀ monotonously increases from 0 to ΔI (5) When X ₀ <x · x ′ f (x · x ′) = + ΔI
Here, X ₀ is a parameter for adjusting a range in which the bias current continuously changes.

Next, a modification of the displacement sensor that detects the amount of displacement of the floating object in the lateral displacement direction will be described.
As shown in FIG. 1, the displacement sensor 20 arranged in the lateral direction of the flying object 11 may be in the way.
FIG. 13 shows a configuration in which the sensing coil 201 is arranged on the side of the electromagnet facing the floating object to detect vibration in the lateral displacement direction of the floating object.
In the sensing coil 201, when the magnetic flux passing through the coil changes, an induced electromotive force is generated and an induced current flows. When the levitating object is displaced in a direction away from the center of vibration, the magnetic flux passing through the coil is reduced. When the levitating object is displaced in a direction returning to the vibration center, the magnetic flux passing through the coil is increased. Therefore, the direction of the induced electromotive force is reversed between the state of x · x ′> 0 and the state of x · x ′ <0, and whether x · x ′> 0 or x · x ′ <0 from the direction of the induced current. Can be identified.

FIG. 14 shows a configuration in which an electromagnet is supported by a force sensor 202 and vibrations in the lateral displacement direction of a floating object are detected from a detection signal of the force sensor 202.
When the floating object is displaced in a direction away from the center of vibration, the detection signal of the force sensor 202 shows a decreasing tendency, and when the floating object is displaced in a direction returning to the center of vibration, the detection signal of the force sensor 202 is detected. Shows an increasing trend. Therefore, it can be identified from the detection signal of the force sensor 202 whether x · x ′> 0 or x · x ′ <0.
In this way, by adopting the configuration of FIG. 13 or FIG. 14, the displacement sensor on the side of the magnetic levitation device can be removed.

(Second Embodiment)
FIG. 15 shows a repulsive magnetic levitation apparatus according to the second embodiment of the present invention.
This apparatus includes a pair of permanent magnets 150 and 160 disposed to face each other in the lateral direction (z direction), a magnet holding portion 151 that can move in the z direction while holding the permanent magnet 150, and the permanent magnet 160. Magnet holding part 161 that can move in the z direction while holding the magnet, permanent magnets 711 and 712 repelling the permanent magnet 150, permanent magnets 721 and 722 repelling the permanent magnet 160, and the permanent magnet 711 on the inner wall 712 and permanent magnets 721 and 722 are fixed, and a control mechanism 80 that controls the moving positions of the magnet holding part 151 and the magnet holding part 161 in the z direction is provided.
Although the permanent magnet 150 is shown as one cylindrical permanent magnet fixed to the shaft 512 of the magnet holding portion 151, the permanent magnet 150 may be composed of a plurality of permanent magnets arranged vertically symmetrically about the shaft 512. good. The same applies to the permanent magnet 160.
The permanent magnets 711 and 712 may be a single cylindrical permanent magnet fixed to the cylindrical inner wall of the levitating object 170, or may be a plurality of symmetrically arranged upper and lower on the inner wall of the levitating object 170. A permanent magnet may be used. The same applies to the permanent magnets 721 and 722.
In any case, the portions 711 and 712 of the permanent magnet of the floating object 170 repel each other in the direction opposite to the permanent magnet 150, and the portions 721 and 722 of the permanent magnet of the floating object 170 are repelled. Is repelled in a direction opposite to the permanent magnet 160, and the levitated object 170 may be supported by the permanent magnets 150 and 160 in a non-contact manner.

  When a displacement signal (z) is input from a displacement sensor (not shown) that detects the displacement of the flying object 170 in the z direction, the control mechanism 80 includes a magnet holding unit 151 for canceling the displacement in the z direction by PID control, and When a displacement signal (x) is input from a PID control unit 81 that calculates the amount of movement of the magnet holding unit 152 in the z direction and a displacement sensor (not shown) that detects displacement in the x direction accompanying the vibration of the floating object 170 in the x direction. The vibration suppression movement amount switching unit 87 outputs Δz as the z direction movement amount when x · x ′> 0, and outputs −Δz as the z direction movement amount when x · x ′ <0, and vibration suppression An inversion unit 82 that inverts the sign of the z-direction movement amount output from the movement amount switching unit 87, and an addition unit 83 that adds the z-direction movement amounts output from the PID control unit 81 and the vibration suppression movement amount switching unit 87; , PID control unit 81 and From the addition unit 84 that adds the z-direction movement amount output from the reversing unit 82, the drive unit 85 that moves the magnet holding unit 151 in the z direction by the z-direction movement amount output from the addition unit 83, and the addition unit 84 And a drive unit 86 that moves the magnet holding unit 161 in the z direction by the output z-direction movement amount.

In this apparatus, when the floating object 170 is displaced in the z direction, the magnet holding part 151 and the permanent magnet 150, and the magnet holding part 152 and the permanent magnet 160 are the same distance in the same direction in the z direction so as to cancel the displacement. Just move. The flying object 170 is stably supported in a non-contact manner in the z direction by this feedback control.
However, since active control does not work in the x direction perpendicular to the arrangement direction of the pair of permanent magnets 150 and 160, vibration in the x direction (vibration in the lateral displacement direction) is difficult to attenuate.

  In order to attenuate the vibration in the lateral displacement direction, a z-direction movement amount corresponding to the sign of x · x ′ is output from the vibration suppression movement amount switching unit 87 and the reversing unit 82. Since the z-direction movement amount output from the vibration suppression movement amount switching unit 87 and the reversing unit 82 defines a symmetrical movement between the magnet holding unit 151 and the magnet holding unit 152, a pair of permanent magnets 150, 160 moves the same distance in the opposite direction in the z direction. The symmetrical movement of the permanent magnets 150 and 160 does not disturb the balance of the floating object 170 in the z direction.

FIG. 16A shows the positional relationship between the permanent magnets 150 and 160 and the floating object 170 when x · x ′> 0, and FIG. 16B shows the permanent relationship when x · x ′ <0. The positional relationship between the magnets 150 and 160 and the floating object 170 is shown.
In the state of FIG. 16A, the permanent magnets 150 and 160 and the permanent magnet of the levitated object 170 are facing each other, and a strong repulsive force is acting between them. Therefore, the rigidity against displacement (lateral deviation) in the x direction is high. On the other hand, in the state of FIG. 16B, the permanent magnets 150 and 160 and the permanent magnet of the levitated object 170 are not facing each other, and the repulsive force between them is weak. For this reason, the rigidity against lateral displacement is low.
In this way, when x · x ′> 0, the rigidity is set to be strong, and when x · x ′ <0, the rigidity is set to be weak, as in the first embodiment. Directional vibrations converge rapidly.

  The magnetic levitation apparatus of the present invention has an advantage that it can stably support non-contact of an object to be levitated, and can be configured in a small size and at a low cost. The present invention can be widely used for apparatuses having a suction type or repulsive type magnetic levitation system, such as a transfer device or a gyro sensor.

DESCRIPTION OF SYMBOLS 10 Electromagnet 11 Ferromagnetic material 12 Electromagnet 20 Displacement sensor 40 Control mechanism 41 PID control part 42 Inversion part 43 Adder part 44 Adder part 45 Amplifier 46 Amplifier 47 Bias current switching part 50 Levitation target 51 Electromagnet 52 Electromagnet 53 Voice coil motor 54 Laser Displacement meter 55 Leaf spring 80 Control mechanism 81 PID control unit 82 Inversion unit 83 Addition unit 84 Addition unit 85 Drive unit 86 Drive unit 87 Vibration suppression movement amount switching unit 150 Permanent magnet 151 Magnet holding unit 160 Permanent magnet 161 Magnet holding unit 170 Levitation Object 201 Sensing coil 202 Force sensor 711 Permanent magnet 712 Permanent magnet

Claims (11)

A magnetic levitation device for supporting a levitated object in a non-contact manner using magnetic force,
A pair of magnets that generate magnetic force for non-contact support of the floating object;
A displacement detection means for detecting displacement of the floating object in a lateral displacement direction perpendicular to the arrangement direction of the pair of magnets;
Control means for suppressing vibration in the lateral displacement direction of the floating object;
With
The control means controls the pair of magnets so that a stronger magnetic force acts on the levitating object displaced in a direction away from the center of vibration than when displaced in a direction returning to the center of vibration.
A magnetic levitation device.   2. The magnetic levitation apparatus according to claim 1, wherein the pair of magnets is an electromagnet arranged in a vertical direction, and the floating object is attracted to each of the electromagnets and is not in contact with the pair of electromagnets. The control means includes a ferromagnetic body supported, and the control means increases the current applied to the pair of electromagnets when the floating object is displaced in a direction away from the center of the vibration, and the floating object is A magnetic levitation apparatus characterized by weakening a current applied to the pair of electromagnets when displaced in a direction returning to the center.   3. The magnetic levitation apparatus according to claim 2, wherein when the displacement of the levitating object vibrating in the lateral displacement direction is x and the moving speed of the levitating object is x ′, the control means The bias current applied to the electromagnet is switched between a state of x · x ′ ≧ 0 and a state of x · x ′ <0, and the bias current when x · x ′ ≧ 0 is x · x ′ <0. The magnetic levitation apparatus is set so as to be larger than the bias current at the time.   4. The magnetic levitation apparatus according to claim 3, wherein when the value of x · x ′ is smaller than a predetermined value, the control unit determines the bias current applied to the pair of electromagnets according to the value of x · x ′. A magnetic levitation device characterized in that   5. The magnetic levitation apparatus according to claim 1, wherein the displacement detection unit is a measurement unit that is disposed in a lateral displacement direction of the levitation object and measures a distance to the levitation object. A magnetic levitation device characterized by that.   5. The magnetic levitation device according to claim 2, wherein the displacement detection unit is a sensing coil that is disposed on a side of the electromagnet facing the levitation object and detects a change in passing magnetic flux. There is a magnetic levitation device.   5. The magnetic levitation apparatus according to claim 2, wherein the displacement detection means is a force sensor that supports the electromagnet and detects a force acting on the electromagnet. Levitation device.   2. The magnetic levitation apparatus according to claim 1, wherein the levitated object includes a magnet repelling in a direction opposite to the pair of magnets, and the repulsion between the pair of magnets and the magnet of the levitated object. The floating object is supported in a non-contact manner by force, and the control means moves the pair of magnets to a position where the repulsive force is increased when the floating object is displaced in a direction away from the center of vibration. The magnetic levitation apparatus, wherein the pair of magnets are moved to a position where the repulsive force is weakened when the levitating object is displaced in a direction returning to the center of the vibration. A control method for a magnetic levitation device that uses a magnetic force to support a levitated object in a non-contact manner,
Between the pair of electromagnets arranged in the vertical direction, support the floating object including the ferromagnetic material in a non-contact manner,
With respect to the pair of electromagnets, a current i that suppresses displacement of the floating object in the arrangement direction of the electromagnets, and a bias current Δi that suppresses vibration of the floating object in a lateral displacement direction orthogonal to the arrangement direction. Are superimposed and applied.
When the displacement of the floating object vibrating in the lateral displacement direction is x and the moving speed of the floating object is x ′, the bias current Δi applied to the pair of electromagnets is in a state of x · x ′ ≧ 0 And x · x ′ <0, and the bias current when x · x ′ ≧ 0 is larger than the bias current when x · x ′ <0.
A control method for a magnetic levitation apparatus.   10. The method of controlling a magnetic levitation apparatus according to claim 9, wherein when the value of x · x ′ is smaller than a predetermined value, the bias current Δi is decreased according to the value of x · x ′. A control method of the magnetic levitation apparatus. The method of controlling a magnetic levitation apparatus according to claim 10, wherein the bias current Δi is changed according to a function f (x · x ′) that satisfies the following conditions 1 to 5: Device control method.
A parameter for adjusting the range in which the bias current Δi continuously changes is X ₀ ,
Condition 1: When x · x ′ <− X ₀ f (x · x ′) = − ΔI
Condition 2: When −X ₀ <x · x ′ <0, monotonically increases from −ΔI to 0 Condition 3: f (0) = 0,
Condition 4: When 0 <x · x ′ <X ₀ , monotonically increases from 0 to ΔI Condition 5: When X ₀ <x · x ′ f (x · x ′) = + ΔI

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